function tung(t1,t2,t3,t4){
    document.getElementById(t1).style.borderBottom='1px solid black';
    document.getElementById(t2).style.borderBottom='none';
    document.getElementById(t3).colSpan="3";
    document.getElementById(t3).style.display="block"; 
    document.getElementById(t3).style.borderBottom='1px solid black';
    document.getElementById(t4).style.borderBottom='1px solid black';
}

function sanpham(t1,t2,t3){
    document.getElementById(t1).style.borderBottom='none';
    document.getElementById(t2).style.borderBottom='1px solid black';
    document.getElementById(t3).style.borderBottom='1px solid black';    
    return false ;
}

function tung1(t1,t2,t3){
    document.getElementById(t1).style.display="none";
    document.getElementById(t2).style.borderBottom='1px solid black';  
    document.getElementById(t3).style.borderBottom='1px solid black';
}